This invention relates to fluid displacement apparatus, and in particular, to fluid compressor units of the scroll type.
Scroll type apparatus has been well known in the prior art as disclosed in, for example, U.S. Pat. No. 801,182, and others, which include two scroll members each having an end plate and a spiroidal or involute spiral element. The scroll members are maintained angularly and radially offset so that both of spiral elements interfit so as to maintain a plurality of line contacts between the spiral curved surfaces to thereby seal off and define at least one fluid pocket. The relative orbital motion of the scroll members shifts the line contacts along the spiral curved surfaces and, therefore, the fluid pocket changes in volume. The volume of the fluid pocket increases or decreases dependent on the direction of orbital motion. Therefore, scroll-type apparatus is applicable to compress, expand or pump fluids.
In comparison with conventional compressors of the piston type, a scroll-type compressor has advantages, such as a lesser number of parts, continuous compression of fluid and others. However, there have been several problems; primarily sealing of the fluid pocket, wear on the spiral elements, and inlet and outlet porting.
Although many patents, such as, U.S. Pat. Nos. 3,884,599, 3,924,977, 3,994,633, 3,994,636, and 3,994,635 have attempted to resolve these and other problems, the resultant compressor is complicated in construction and in production. Furthermore, because a plurality of spaced radial bearings are used to support the drive shaft, the axial length of the drive shaft is increased so that the resultant compressor is increased in length, volume and weight.
In compressors of this type, lubricating systems are also required for lubricating the moving parts.
Since a compressor of this type is compact and light, it is advantageously used as a refrigerant compressor for a air conditioner in an automobile. However, if an automobile engine is used as a power source for the compressor, the compressor is driven at various speeds dependent on the rotational speed of the automobile engine. Therefore, the amount of compressed fluid discharged during a unit of time at a time when the speed of the automobile engine is, for example, 5,000 r.p.m., is much more than that at a time when the speed of the automobile engine is 1,000 r.p.m. Such a large variation in the amount of compressed fluid supplied is not desirable in the refrigerant circulating circuit which is connected to the compressor.